Semiconductor device and manufacturing method thereof

A semiconductor device, comprising:

• a semiconductor substrate having thereon a first MIS transistor and a second MIS transistor that are separated from each other by an isolation region, wherein
• the first MIS transistor includes
• a first active region surrounded by the isolation region in the semiconductor substrate,
• a first gate insulating film formed on the first active region,
• a first gate electrode formed on the first gate insulating film,
• a first insulating sidewall spacer formed on a side surface of the first gate electrode, and
• a first source/drain region formed outside the first insulating sidewall spacer, as viewed from the first gate electrode, in the first active region,
• the second MIS transistor includes
• a second active region surrounded by the isolation region in the semiconductor substrate,
• a second gate insulating film formed on the second active region,
• a second gate electrode formed on the second gate insulating film,
• a second insulating sidewall spacer formed on a side surface of the second gate electrode, and
• a second source/drain region formed outside the second insulating sidewall spacer, as viewed from the second gate electrode, in the second active region,
• the second source/drain region includes a silicon mixed-crystal layer, and
• the second gate electrode has a lower height than the first gate electrode.